The present invention relates to an electronic map display system for visually displaying map data stored, or more in particular to an electronic map display system suitable for use on an automobile or the like.
A conventional device called an electronic map display system has been suggested in the art. Using this device, necessary map can be rapidly searched for is used by the automobile driver to enable him to reach his destination.
In such a system, required map data on given areas are stored in a large-capacity memory means such as a magnetic disc or optical disc, and by designating the area around the automobile with a select switch or the like, the map thereof is displayed on a CRT or the like device.
Data memory means for this display has so far been limited generally to an image pattern system, in which images of maps are stored. A map image, for example, is subdivided and each divided unit is stored in an arrangement corresponding to the particular map coordinate as digital data.
Using such an electronic map display system, it is no longer necessary to carry any map while driving, and a required place can be easily searched for.
The above-mentioned image pattern system stores all the points on a map. Since a very great amount of memory areas is required, either the memory medium is required to be enlarged or the storage amount is required to be decreased by limiting the display.
Another disadvantage of the image pattern system is that the construction of the map elements cannot be identified and it becomes very difficult to change the form in which the contents of the map will be displayed by data conversion, so that it is necessary to store the data on the whole screen for each form of expression including enlargement, reduction, resolution or color.
Further, the problem is that the change or correction of a part of the data requires replacement of the whole data.